Rinse the strawberries. Trim and chop them. Wash the lime well and finely grate the zest. Juice the lime and lemon. Mix the juices in a bowl with the zest and mint. Gently stir the strawberries into the marinade and refrigerate for 1 hour. Whip the cream with the vanilla sugar until it forms soft peaks. Stir the crème fraîche until smooth, then fold into the cream. Chop up the chocolate wafer. Layer the strawberries, chocolate wafer and cream in glasses.